Wash box discharge control



April 17, 1956 c, w, LOTZ ETAL (2,742,153

- WASH BOX DISCHARGE CONTROL 7 4 Sheets-Sheet 1 Filed Oct. 5. 1952INVENTORS Charles W Lotz Q CMrmae 111. Kazmier 1y ;ORNEY April 17, 1956c. w. LOTZ EI'AL WASH BOX DISCHARGE CONTROL 4 Sheets-Sheet 2 Filed Oct.5. 1952 v 1 m 4 m H I v n M 1 J 2:: a a IUVUI z fl 9 9 lnz gzliw 0 Mn 02lul- $12 Charles 715L051 Qzd April 17, 1956 c. w. LQTZ arm. 2,742,153

WASH BOX DISCHARGE CONTROL 4 Sheets-Sheet 5 Filed Oct. 3, 1952 \SUPPLYAIR INVENTORS Charles W L052 Qd ClarmwMKazmier April 17,1956

Filed Oct. :5, 1952 c. w. LOTZ ETAL 2,742,153

WASH BOX DISCHARGE CONTROL 4 Sheets-Sheet 4 IN VENTORS Cizwrhs MC L022Q61 ClarazceMKwzmier QQZ United States Patent WASH BOX DISCHARGE CONTROLCharles W. Lotz and Clarence M. Kazmier, Chicago, Ill.,

assignors to Link-Belt Company, a corporation of Illinois ApplicationOctober 3, 1952, Serial No. 312,982

18 Claims. (11. 209--496) This invention relates to new and usefulimprovements in wash box discharge controls and deals more particularlywith an automatic discharge control adapted to vary, through a rangeofvalues, the rate of discharge of the high gravity stratum from a washbox which is designed for handling coal or other minerals.

Due to the wide variation in the ratio of high to low gravity particlesoccurring in the minerals normally processed in a wash box, the rate ofaccumulation of the high gravity particles in the bottom of the washbox'will also vary considerably over a given period of time. It isconventional practice, therefore, to intermittently discharge the highgravity particles in accordance withthe depth of the bed or stratum ofsuch particles in the Wash box.

One form of automatic control of the discharge of the high gravityparticles has, in the past, provided on and V oii' operation with, insome instances, two rates of discharge in the on position. Since therate of accumulation of the high gravity particles in the bottom of thewash box seldom equals the rate of discharge afforded by this type ofcontrol, changes from the off to the on position or between the twospeeds in the on position were frequent and caused the operatingcharacteristics to be somewhat irregular. For example, if the rate ofaccumulation fell just below the rate of discharge at the higher of thetwo speeds, the stratum of high gravity particles would increase indepth until the control device actuated the high speed discharge. Thedepth of the stratum would then drop and the speed of discharge would bereduced to its lower value whereupon the depth of the stratum wouldagain increase. With each of these changes, the pressure required topulsate the hutch water in the wash box and the stratifying action ofthe hutch water would be varied. v

A common prior art type of control has been dependent upon the use of afloat having'such a specific gravity that r i it responded to changes inthe depth of the stratum of high gravity particles and thus regulatedthe discharge of the such particles in accordance with the response. Theuse of such a float type control necessarilyinvolves 2,142,153 PatentedApr. 17, 1956 r6 ICC tions due to changes in the. total depth of thehigh and low gravity strata and the size consist. I p

Other objects and advantages of the. invention will be apparent duringthe course of the following description;

.In the accompanying drawings forming a part of this specification andin which like reference characters are employed to designate likepartsthroughout the same,

Figure 1 is a fragmentary elevational view, partly broken away, of thedischarge end portion ofa wash box embodying this invention, i I

Figure 2 is a vertical sectional view of the discharge chute andgateillustrated inFig. 1, I

Figure 3 is an elevational view, partly in cross-section, of thestep-by-step drive for the discharge gate and the mechanism foradjusting the drive,

Figure 4 is a fragmentary elevational view,; partly broken away, showingthe connection between ;the drive adjusting mechanism and its actuationcontroller,

Figure 5 is a. detail elevational view of the discharge gate driveillustrated in Fig. 3, 1 v

Figure 6 is a fragmentary sectional view ofthe actuation controller forthe drive adjusting mechanism,

Figure 7 is a perspectiveview showing the arrangement of and connectionsbetweenthe control elements within the control housing illustratedinFig. 1, t

Figure 8 is a detail side elevational view of the switch operating camand follower illustrated in Fig. 1,

Figure 9 is a partly 'elevational view. and 'partlyzsectional view oftheswitch and cam illustrated in Fig. 8,

Figure 10 is a schematic view of two of the"control elements illustratedin- Fig. 7, and

Figure 11 is a schematic view ofthe differential pres sure relay and thefiowindicator and reducing valve of Fig. 1. t

is shown a preferred embodiment of this invention," and firstfparticularly referring to Fig. 1, there is shown a commercial form ofwashing jig that includes a wash box 11 which has its upper portiondivided into front and rear sections by the longitudinally extendingpartition 12. These two sectionsof'thewash' box 11 are inop'encommunication beneath the lower edge of the partitiorilZ which lies inspacedrelation to the bottom of the wash box. 'A pressure tight cover 13closes the top of the rear longitudinal section. t

The front longitudinal section of the wash boxll is provided with amaterial bed supporting screen 14 having a downwardly inclined endportion 15 which acts as i a discharge chute. The lower end portion ofthe dissubjecting the fioat to abrasion and corrosion and, there- Ifore, requires a substantial amount of maintenancefor properfunctioning. Further; when itv is. desired to change the depth orconsistency of the high gravity stratum, mechanical adjustment of thecontrol system, or changes in the weight of the. float assembly, areinvolved.

It is the primary object of this inventionto provide a control devicefor use in connection with wash boxes to automatically regulate the rateat which the high gravity particles are continuously dischargedtherefrom, in 'response to changes in the pressure required to;force thewash water through the stratum of such particles, so as to maintain at asubstantially constant depth the stratum of such particles in the washbox. 7

A further object of the invention is to provide a wash rate at which thehigh gravity particles are continuously charge chute 15 isenlarged andso-formed as to receive a rotary discharge gate .16 mounted on andcarried by the shaft 17, as illustrated in Fig. 2. A slide gate 18 actsto regulate the effective depth of the discharge chute 15 and is carriedby a rod '19 having its upperend portion in the form of a rack 21 for"engagement with the pinion 22 keyed to the shaft 23 which may berotatedto rais'e'or lower the slide gate 18. 1

The end wall of the wash boxll above the discharge chute 15-is providedwith an exit sluice 24. "An inlet sluice, not shown, similar to t'heexit sluice 24 may be utilized to introduce material to the opposite endportionofthewashboxll. i When the illustrated washing jig is inoperation, the wash box 11 is provided with water up to the desiredlevel. The pressure tight rea-r longitudinal section is corinected to acompressed air receiver 25 through the. air inlet pipes 26 which areprovided with valves 27 that In the drawings, wherein for the purpose ofillustration,

are operated "simultaneously by the earns 28, rotated by the camshaft29, to impart reciprocating motion to the valve operating rods 31, asillustrated in Figs. 8 and 9.

When the valve operating rods 31 are in their lower positions, thevalves'27 permit compressed air to flow from the receiver 25 through theair inlet pipes 26 into the longitudinal section at the rear of the washbox 11. This compressed air'forces the water in the rear section to passunder the lower edge of the partition 12 to force the water in the frontsection "to rise through the material bed supporting screen'14'and thematerial bed B. When the valve operating rods 31are in their upper twoend positions of oscillation of the radial arms 38 and pawl 39 areillustrated by broken lines in Fig. 3 and the pawl 39 is lifted out ofengagement with the ratchet wheel 42 during a major portion of itsoscillating movement. Rotation of the cam discs 43 to relocate theirstepped portions 44, therefore, acts to determine that portion of thepath of travel of the radial arms 38 through which the pawl 39 engagesthe ratchet teeth.

' Each cam disc 43 is provided with an extension arm positions, thevalves 27 act to close the air inlet pipes 26 and exhaust the compressedair from the rear longitudinal'section. The water in the front sectionofthe wash box will, therefore,s'eek the level of the water in the rearsection whereby the water in the front section passesdownwardly throughthe material bed B and its supporting screen 14.

A starting mixture of mineral particles of different specific gravitiesand wash water-is sluiced, or otherwise introduced, into the feed end ofthe front section of the wash box 11. The mineral particles will beadvanced lengthwise of the front section by the longitudinal hydraulicflow through the wash box 11. While advancing toward the exit end ofthewash box 11, the mineral particles of different specific gravitiesare'stratified by the pulsations of the water so that the higher gravityparticles are concentrated at the bottom of the material bed B and canbe withdrawn through the discharge gate 16. The lower gravity particleswill collect along the upper stratum of the material bed B and willspill into the exit sluice 24 with a'certain amount of water during eachpulsion stroke.

' The above structuralfeatures of the washing jig are conventional andare more completely illustrated and described in the copending CharlesW. Lotz application,

Serial No. 148,213, filed March 7, 1950, now Patent No.

2,609,098, for Method of and Apparatus for Continuously Cleaning andSeparating Minerals of Different Specific Gravities, which applicationis a continuation-inpart of application, Serial No. 753,524, filed June9, 1947 and now abandoned, and bearing the same title.

The discharge gate 16 and its drive mechanism are of the typeillustrated and described in the patent to E. J. Burnell et al.,-No.2,106,204, dated January 25, 1938, ,and will be only briefly describedas follows:

The motor 32, having a starting switch 33, is connected by a belt 34 toa speed reducer 35. It is to be understoodthat a direct'coupling orother suitable device I may beused to 'drivingly connect the motor 32 tothe speed reducer 35.. The speed reducer 35 is provided with a crank arm.36 having a connecting rod 37 pivoted to its outer end portion. As isillustrated in Figs. .1, 3 and 5, the other end portion of theconnecting rod 37 is pivotally connected to a radial arm 38 which isfree to pivot about the shaft 17. The length of the radial arm 38 isgreater ,than the length of .the crank arm 36 so that rotation of thecrank 'arm acts through the connecting rod- 37 to impart oscillatorymotion to the radial arm 38. The radial arm 38 carries .a pawl 39 whichis depressed by the spring 41 for engagement with the teeth of a ratchetwheel 42 which is keyed to the shaft 17'. The oscillating motionof theradial arm 38, therefore, imparts an intermittent rotation to thedischarge gate 16 which is carried by the shaft 17.

Control of the effective length of intermittent rotary motion of thedischarge gate 16, as illustrated in Figs. 3 and 5, is provided in thefollowing manner: A pair of cam discs 43 are rotatably mounted on theshaft 17 adjacent opposite sides of the ratchet wheel 42 and are eachprovided with a similarly located stepped portion 44 for engaging aroller 45 on the pawl 39 to liftthe pawl from engagement with theratchet during a 46, and a pin 47 connects the two extension arms to oneend portion of an operating rod 48. Movement of o the operating rod 48,therefore, will simultaneously rotate both of the cam discs 43 to effectthe desired relocation of their stepped portions 44 so that the pawl 39will impart the desired amount of intermittent rotary motion to thedischarge gate 16. In addition to the arms 46 and pin 47 the cam discs43 are rigidly connected to each other by oppositely arranged pairs ofarms '49 and 51, and pins 52 and 53, respectively, which connect thearms of each pair.

The starting switch 33 of the motor 32 is connected to a source ofsupply of electric energy through the lead wires C, D and E and themotor is operated continuously during the periods of operation of thewash box 11. The rate of rotation of the discharge gate 16 in the chute15, however, is controlled by an automatic control system which isresponsive to the depth of the stratum of heavier particles thataccumulates adjacent the material bed supporting screen 14. In otherwords, when the stratum of heavier particles increases in depth thedischarge gate is operated at a faster rate to increase the discharge ofheavier particles through the chute 15. When the depth of the stratum ofheavier particles decreases, the cam discs 43 are adjusted to decreasethe rate of discharge by the gate 16 with the final result that thethickness of the stratum of heavier particles remains at a substantiallyconstant value.

The present invention provides for the above discussed control of thethickness of the stratum of heavier particles in response to changes inthe pressure required to force the wash water through the material bed 3as the thicknessof the stratum of heavier particles varies. As waspreviously pointed out, the rate of discharge of the heavier particlesis adjusted by movement of the operating rod 48 to vary the position ofthe cam discs 43 and the desired control of the discharge rate is,therefore, accomplished by properly positioning the operating rod inaccordance with the hydrostatic pressure of the wash water in the bottomof the material bed B.

Referring now to Fig. 1 for a brief description of the complete systememployed for controlling'the.operation of the discharge gate 16,reference character 57 designates a pipe or tube, connected to asuitable source of compressed air, not shown, for supplying air to thecontrol system at a pressure of between 30 and lbs. per square inch. Thecompressed air flowing through the tube 57 successively "passes througha trap 58, which removes water, oil and dirt from the air, and apressure reducing valve 59 from which the air flows at a reducedconstant pressure of, for example, 20 lbs. per square inch. The air fromthe pressure reducing valve 59 passes into a suitable coupling 61 whereit is divided for How into three separate branches of the controlsystem.

One of these branches leading from the coupling 61 passes through, aconstant differential pressure relay 62, a flow indicating device 63 anda throttle valve 64 which is combined with the flow indicating device.As illustrated in Fig. 11, the differential pressure relay 62 includes avalve 65, or similar flow restricting device, which is operated by adiaphragm 66 one side of which is exposed to theconstant pressure of 20lbs. per square inch of the air entering the relay. The other side ofthe diaphragm 66 is in open communication through the tube 67 with thelow pressure side of the throttle valve 64. The-valve 64 reduces thepressure of the air flowing through the indiwash box 11;

email-a *5 eating device: 632 to a value: offapproxiinately' 3 lbs. persquare inch but; as. will: betlater described;, the pressure orrthe'l'owsid'ev'of the throttle valve. 64 will vanyr through a' relatively smallrange during: each pulsion of the water in the-'washbox-ll and willalsovary:in:.accordance'with the;depth.=.of the: stratum oft highgravity; particles: in the In orderto maintain-the: rate of. flowofiair' through the throttlevalve: 64 ata. constant value despitefluctuations. in the pressure; on: the low side of. the valve, thepressure drop: across the: valve 64-must bemaintai'ned': at a: constantvalue; This is; accomplished by subj'ecting one side ofv the diaphragm:66nto; the varying pressures on the low side ofithe: valve 64.? whilethe pressure on: the opposite side. of: the: diaphragm is. maintained ata constant valueof 20 lbs. per square inch. The varying pressureto:which.the one side-of the diaphragm 66 is exposed will. cause thevalve 65-.to be'opened or closed a sufiici'ent amount: to maintain thepressure of: the air enteringthe-throttle valve 64xat the-desired valueabove that of the air on the low pressure side of: thiselatter' vallve.In

this manner, the rate at which the: compressed air flows from the valve64 into thetube 68' is maintained at a constant' value despite limitedvariations inJthe pressure ofv the air in the tube.

- Referring once again to Fig. 1,.theairfrorn the valve 64 fiowsthroughthe tube 68 to a. pipe 69 which: extends downwardly through the materialbed Bin the wash box 11 to the supporting screen 14; The level. of. thewater in the wash box 11 will, of course',.varyi with each pulsathe"tube 72 passes through 'amanually operated valve 75and into the encasedportion ofthe control. system which is designated in its entiretyiby thereference character 76 and which will be morefully' desribed'at alaterPoint.

Neglecting the insignificant amount of friction between the pipe 69'andthe air flowing therethrough, the pressure of the air in the'pipe may beassumed to be equal "to "the pressure exerted by the water resisting thedischarge of the'air from the opening171; This hydrostatic pressurewill, of course,.vary during each pulsion stroke of-the water but, at agiven point during each-such stroke, the pressure will vary primarily inaccordancewith thethickness, and, therefore, the-hydraulic resistance,ofthe material bed B to the flow of the water therethrough. In order toprevent large fluctuations of pressure in the tube 72 during successivepulsion strokes'of the water, the actuation of the solenoid valve 73' istimed to provide comrnunication between the tube 72' and the pipe 69only duringthe same small portion of each-'pulsionstroke. The pressurein the tube 72, therefore, is relatively constant, and will vary only inaccordance with changesin the'pressure of the water at the opening 71which result from changes in the hydraulic resistance of the-stratumofheavier particles in the bottom portion of the material bed-B. q

Intermittent action 'ofthe" valve 73 in the manner described aboveresults from a similarly intermittent actu'ation of the solenoid 74which is accomplished by a switch 76' mounted on one of the valveoperating rods 31, as illustrated in Figs. 1 8 and 9', and a" switchoperating, lug 77 arranged to engage the operatinglever 78 of the switch76for a given portion and ma given point of each revol'ution ofthe cam28'. Inasmuch asthecam28 controls the operation of thevalve 27 and,therefore; the pulsations of the washwater and the operating lug: 77controls the act uati'on of the. switch: 76 to open and closevthevalve73,

6 28 will provide for synchronization oi the; operation of the valve 733with the: pulsations: oi the: wash water;

The-wires F and G-areconnected to a suitable: source of supply ofelectric energy for operating the valve 73 through the switch 76: andthe solenoid 74; One side of the switch 76' is. connected to the wire Fand the other side of the switch is connected throughthe solenoid 74 tothe wire: G. i

A second. branch of the control system is connected directly to thecoupling 61 by the tube 79 which extends to the encased portion 76 ofthe control system.

A third branch of the controlsystem extends from the coupling 61 throughthe tube 81 to a pilot valve'housing 82 whichis illustratediin Fig. 6 asbeing provided with an inlet port 83, an exhaust port. 84 and an outputport 85 in additionto a control port 86 through which compressed air isadmitted to automatically control the operation of the pilot valve 87.The: automatic operation of the pilot valve 87 willbemorefully'described at a later point but at this time it will benotedthatthe position of the pilot valve controls both the amount of air thatflows through the inlet port. 83 and the tube 81 and the portion of thisair that. is vented to the atmosphere through the exhaust port 84 tothereby control the pressure of the air at the output port 85. In otherwords, the pressure of the air at the port 8S may be increased,decreased or maintained at a constant value depending upon the positionof the pilot valve 87..

. Thetube 83 that is connected to the output port 85 is illustrated in.Fig. 3' as providing communication with the chamber 89 located in theupper portion of the operating rod positioning device 91. One wall ofthis chamber 89" is formedby a diaphragm 92 which is actuated inaccordance with the pressure of the air in the chamber 89. The diaphragm92 and its backing plate 93 are urged in a direction to oppose thepressure of the air in the chamber 89 by a spring 94 and the upper endportion of therod' 48', whichrotates the cam disc 43, is connected tothe backing. plate. Downward movement of the diaphragm 92 caused by theair pressure in the chamber 89 is limited by engagement of the stop 95on the backing plate 93 and the stop 96 on the supporting frame of thepositioning device 91.

It will be: readily apparent, therefore, that as the pressure oftheairin the chamber 89 is increased or decreased or: is maintained at aconstant value, within the range of fronrO to 20'lbs. per square inch,the cam disc operating me 48 will. bemoved, respectively, downwardly orup- Wardly or will be maintained in a stationary position.

Downward movement of the rod 48 will cause rotation of thecam discs: 43in a direction to increase the length of throw of the step-by-step drivefor, and the rate of rotation of, the discharge gate 16, while upwardmoveproper mounting of the switch operatinglug 77 on the earn 7 ment oithe rod will decrease said length of throw and rate of rotation.Maintaining the rod in a stationary position will cause the length ofthrow and the rate of rotation to be maintained at a correspondingconstant value.

The control port 86 of the pilot valve. housing 82, through whichcompressed air is admitted to control the operation of the pilot valve87, is illustrated in Fig. 1 as being connected to the encased portion76 of the control system hya' tube 98.

Referring now to Figs. 7 and 10 for a detail description of the portionof the control system that is housed in the" casing 76, and firstparticularly referring to Fig. 7, the tube 721 which is in intermittentcommunication with the pipe69 through the valve 73, during like portionsof successive pulsations of the wash Water, is connected to apressurebellows 99 which will expand or contract as thepressure in the tube 72increases or decreases, respectively. It. will be appreciated that anypressure responsive or pressure measuring gauge capable of producing a;change in position of a signal element may be substituted for thepressure bellows disclosed. The bellows 99 is supported at its lower endby a bracket 101 while connected to the free upper end portion of thebellows is a rod 102 which is movable in accordance with the pressure ofthe air in the bellows. The upper end portion'of the rod 102 ispivotally connected to one arm of a crank 103 which is pivotally mountedon and supported by a shaft 104. The other arm of the crank 103 ispivotally connected to one end portion of a link 105 which has its otherend portion pivotally connected to an arm 106 rigidly mounted on therotatable pointer shaft 107. Fixed on one end portion of the shaft 107is an indicating pointer 108 the weight of which is balanced by twocounterweights 109. Changes in the pressure of the air within thebellows 99, therefore, will impart rotary movement to the shaft 107through the above described linkage and will cause movement of thepointer 108 in direct relationship with the changes in the pressure.

A second arm 111 is rigidly connected to the shaft 107 and the outer endportion of this arm is pivotally connected to a measurement link 112which extends to and is connectedwith a vane positioning arm 113 that isrigidly connected to a rotatable shaft 114 upon which is mounted a vane115 having a radial end edge 116. The motion of the pointer shaft 107 istransmitted by the .measurement link 112 to the vane positioning arm 113so that the vane 115. is moved through an arcuate' path as the pressurein the bellows 99 varies.

The tube 79 of the control system is shown in Fig. 7 as being connectedto a pressure gauge 117 which indicates any deviation from the desiredoperating pressure of, for example, 20 lbs. per square inch. From thepressure gauge 1.17, the air flows through a tube 118 to the pilot valveamplifier 119, see Figs. 7 and 10, and, also, through a restrictedorifice 121 to the tube 122. The tube 122 is connected to a jet housing123 which is mounted for pivotal movement concentric with the axis ofthe shaft 114upon which the vane 115 is rigidly mounted. The jet housing123 has branch passageways therein in communication with the tube 122and openingfrom the housing through opposed jets 124 which are arrangedin closely spaced relationship on opposite sides of the path of travelof the vane 115.

Compressed air passing through the tube 122 is continuously dischargedfrom the jets 124 and it will be readily apparent that back pressurewill develop in the tube 122 which will vary in direct relationship withthe portions of the opposed jet openings which are covered by the endedge 116 of the vane 115. Inasmuch as the jet openings are very small,any slight movement of the vane edge relative thereto will effect a verysubstantial variation in the back pressure of the air flowing throughthe tube 122. For example, the orifice 121 and the openings in the jets124 may be so formed that when the vane edge 116 is moved half thedistance across the jet openings the back pressure in the tube 122 willbe equal to lbs. per square inch. Under these conditions movement of thevane 115 through a distance of .0025 inch in one direction will cause anincrease in the back pressure in the tube 122 of /2 lb. per square inchand movement of the vane for a similar distance in the oppositedirection will cause a corresponding decrease in the back pressure inthe tube 122. This combined variation of 1 lb. per square inch in theback pressure in the tube 122 is sufficient to operate the pilot valveamplifier 119 as will be later described.

The jet housing 123 is moved relative to its shaft 114 by means of aset-point knob 125 which rotates the gear set 126 to actuate the rackand pinion 127, the rack of which is connected to the jet housing 123.The rack also is connected through the link 128 andsarm 129 to arotatable shaft 131 which is to berotated by movement of the'jet housing123. Mounted on the shaft 131 and positioned adjacent the pointer 108 isa set-point index 132.

It will be recalled that when the wash box 11 is operating in asatisfactory manner the depth of the stratum of high gravity-particlesin the bottom of *the bed of material B is maintained at a constantvalue by rotation of the discharge gate 16 at a given rate. Thehydrostatic pressure of the wash water at the'opening 71 in the pipe 69will, therefore,remain at a constant low value which is equal to thepressure of the air in the pipe and which iis also equal to the pressureof the air in the bellows 99 during the same portion of successivepulsations of the water. This pressure in thebellows 99 is measured andindicated by the pointer 108 and the set-point knob is rotated to adjusttheposition of the set-point index 132 to correspond to that of thepointer 108. When so adjusted, the'ed'ge 116 of the vane 115 ispositioned relative to'the openings of the jets 124 so as to cover onehalf of the'area of the jet openings. The back pressure in the tube 122will, therefore, be 5 lbs. per square inch. That portion of the airflowing through thetube 79 which passes through the tube 118 to thepilot valve amplifier 119 is admitted to the latter through a supplyport 133 and is discharged through an exhaust port 134 in accordancewith-the position of the ball 135, see Fig. 10. This ball 135 is movedtoward and away from the supply and exhaust ports 133 and 134 by a pin136 which is supported by the diaphragm 137. A light spring 138 urgesthe ball into constant engagement with the'pin 136. As the ball 135 ismoved to vary the rates at which the air is admitted to andexhaustedfrom the pilot valveamplifier, the pressure of the air withinthe amplifier and within the tube 98 is variedin a direct relationship.

In other'words, an increase in the back pressure in the tube.122 istransmitted through the branch tube 139 to the diaphragm 137 where itwill cause movement of the pin 136 to reduce the supply of air to thepilot valve amplifier and to increase the rate at which the air isexhausted through the port 134.. The pressure of the air within the tube98 is thereby reduced in inverse relationship with the back pressure ofthe air in the tube 122. On the other hand, when the back pressure ofthe air in the tube 122 is reduced, the pressure of the air on thediaphragm 137 is reduced .and the ball is permitted to move toward theexhaust port 134. and away from the supply port 133 so that the pressurewithin the pilot valve amplifier is increased to thereby cause anincrease in the pressure within the tube 98. The rate of flow of the airthrough the tube 118 and the size of the supply and exhaust ports 133and 134 are 'such that a variation in the back pressure in the tube122from 4 /2 to 5% lbs. per square inch will cause asvariation of from15 to 3 lbs. per square inch, respectively, in the pressure of the airwithin the tube 98. A back pressure of 5 lbs. per'square inch within thetube 122, therefore, will provide a pressure of 9 lbs. per square inchin the tube 98. I

As illustrated in Fig. 6 the tube 98, leading from the pilot valveamplifier 119, is connected to the control port 86 of the pilot controlvalve 82. The control port 86 is in open communication with the interiorof an annular or double walled pressure bellows 141, the upper closureplate of which is movable by an increase or a decrease in the pressureof the air within the bellows. Supported by the closure plate of thebellows 141 and extending toward the exhaust port 84, is a cylindricalcollar 142 having amounting spider 143 at its lowest end portion forconnection with the operating rod 144 of the pilot valve 87. Theoperating rod 144 extends inwardly through the exhaust port 84and.provides sufficient clearance therewith to permit the free flow of airfrom the port through the spider 143 and the collar 142 for release tothe atmosphere. A balance spring 145 is compressed between the closureplate of the annular bellows 141 and a collar 146 whichis mounted forvertical movement on the shaft 147 and which is adjustable to vary thevertical distance betweenits top surface 148 and the surface againstwhich the spring 145 abuts.

As illustrated in Fig. 3, the top surface 148 of the collar 146 isengaged by the free end of a pivotally mounted arm": 149 wliicli isforced? in a. direction fon engagementwith-.th'e surfaces 148' byaroller." 151 that is: adjustably. mounted on a second arm.15'2.. Oneend: of the arm 152' is pivotallysupportediadjacentthe. free end. ofthearmi149 andf'its other'endiis pivotally connected. to: the. verticallinkt1'5'3.. As illustrated in Figs; 3 aud t, thevertical link.

1'53 is connected tothe'operatingrrod 48* by a.horizontal link-.154. i a

Referring: now to Figs. 31, 4 and 6, andrecallingzthat thepressureiofthe air in the tube 98 will. vary within the range of from 3 to l'S:lbs. pen-square inch and will be: atta pressure of 9 lbs: per squareinch whenithe depth ofi'the stratum of. high gravity particlesv in thewash box 1 1' is at itsdesired. value, the-'operation'of. the pilotcontrol valve87t to regulate the. position of the operating rod 48willibe' describedasifollows:

With the pressure ofthe air in the tube. 98 at a value ofr9- lbs. per.squareinch,the'pressurewithin the bellows 141 will alsobe 9 lbs. persquare inch and the-spring 145Will be adjusted by means of the collar146 to exert an force-on the bellows which= willybalance the force ofthe? air. withinthe bellows. In this connection it will be notedthatwhenthe cam discs-43 and their operating rod 48 are in* the proper positionto provide a rate ofrotation for: the gate 16= which. will maintain aproper. depth for thestratum of high gravity particles, the? arm 149wil1be maintained in a given position by means of the links1'53 and 154'iand the arm 152" and roller. 151. Adjustment ofthe: collar 146;therefore, will be made to. balance the force of the spring 145 againstthe pressure of the air in the. bellows 141'while the .rod 48 is in thisdesired positionr.

Atrise or fall of the pressure of: the": air within the. tube 98s willthereafter. move the pilot valveY87 in: the proper directionto increaseor decrease, respectively, the pressure o t-the air in the tube 88 andinthe diaphragm chamber 89:. As the pressure of tlie air inthe-chamber 89is increased or decreased, the rod. 48 will be repositioned and thecompression of the spring 145* will be varied by themovementsoftthelinks 153 and1154' and the arms 152'and 149 to*rebalancethe forces" applied to theoellows 141 by the: spring 145:and by the.pressure" of the air. within the bellows.

The operations of the various portions of the control system .havebeendescribed above andwill-not be repeated at this time. The operation ofthecontrol. system. as a unit, however, will; be briefly; described asfollows;

.With the discharge; gate 16 rotating at, a properrateto maintain: the:stratum'of' higlr gravity particles in the bed B ofthe'washbox 1 1 atthedesired: depth, the. hydrostratic pressure at the opening. 71 of thepipe 69' is im: pressed-upon the pressure bellows 99' during likeportions of: successive pulsations ofcthe washwater. .This pressurewithinrtheibellows 99 istransmitted through the. linkage whichsconnectssthe bellows .to the: vane 1'15 and: will. position the vane so that itsedge 116 will be midway: across the area. of the opposed: jets:124.'This .position. of the vane 115 will cause the back pressure in the tube122 to equal: lbs. per" square inch which: is the pressure; at which:the'pilotvalve amplifier 119 is. actuated'to provide an=outputpressureof 9 lbs; persquare. inch. This pres+ sure'insthetube 98 is impressedupontheannular: bellows 1x41; to=balanceatheg pilot valve; 87 inazposition atwhich the; pressure inthe tube 88. and chamber89 of thepositioning device: 91,, will: maintain the. operating rod 48 in its.desired position for adjustment of: the cam discsl=43l to provide?theabove: mentioned rate of. rotatiomforf the gate 161. i

'A-ny. deviation in: the: depth. of the'stratum of high gravityparticles from its desired value will cause: a change inthe pressure ofthe airinthe pressure-bellows 9 9 and a change in the position-of thevane- 115' in a direction and by anfamount which are directly,proportionalito the' change of pressure in the bellilws 99. A verysliglit" movement of tlievane 1'159will eifect" a substantial. change in theback pressure in the: tube 122; and an: even; greater}; change in the:output; pressure of the pilot valve amplifier 119 ,in'the tube 98;. Thisampli-. fiedfpressure variation in the tube 98: is impressed upon thebellows 141/to eflect an immediate change in the pressure in the tube 88and the chamber 89which is controlled by the position of the pilot valve87. Variations, of thepressure-inrthe chamber 89 willcause movement of.the operatingmod 48 to properly adjust the position of the cam discs 43to regulate the rate of rotation of the gate 16 andwill rebalance theforces exerted. on the bellows 141 by the spring 145 and by the pressureof the air within. the bellows to recondiwith a ,wash box having a bedof materials therein adapted to be acted upon by a body of washingliquid,

means forproducing apulsating flow of washing liquidv through said bedof materials, a rotary gate for discharging materials from said box, andcontinuously operating drive means for rotating saidgate at avariablerate to control the rate of discharge of materials, of means forintroducing a control fluid directly into and against the variablepressure. of the washliquid at a point at which thepressure of thewashing liquid varies proportionately with changes. in the hydraulicresistance of the material. bed, means for amplifying the pressures ofthe control fluid in said introducing,meansduring. like portions ofsuccessive pulsations ofthe washing liquid, and

fluid pressure operated means responsive to. variations inthe amplifiedpressures for varying the rate at which said gate is rotated to causethe discharge of materials byathe gateto maintain the hydraulicresistance of the bed: substantially constant. 1

2. In; a device of the type described, the combination with a wash boxhaving a bed of materials therein adapted to be acted upon by a bodyofwashing liquid, means for producing. a pulsating: flow of washingliquid through said bedof materials, a rotary gate fordischargingmaterials from said box, and continuously operating drivemeans for rotating said gate at a variable rate to control the rate ofdischarge of materials, of means for introducing a control fluiddirectly into the washing liquid at apoint near thebottom' of said bedand at pressures varying in proportion to the hydrostatic pressures ofthe washing liquid at said point, meansfor amplifying the pressures ofthe control fiuid during like portions of successive pulsations. of thewashing liquid, and means operated by said amplifiedprcssuresfor varyingthe rate at which said' gateis. rotated to vary the material dischargerate through a range of values corresponding to thetvariations in saidhydrostatic pressures of the washingliquid.

. 3'. In adevice of the type described, the combination with a wash box;having a bed of materials therein adapted to be: acted upon by a body ofwashing liquid,

means'for producing a pulsating flow of washing liquid through" said bedof materials, arotary' gate for discharging materials from saidbox, andcontinuously operating drive means for rotating said gate at a variablerate to control the rate of discharge of materials; of a pipe for likeportions of successive pulsations of 'the washing liquid, and meansoperated by said amplified pressures for varying the rate at which saidgate is rotated to vary the material discharge rate through a range ofvalues corresponding to said hydrostatic pressures of the washingliquid.

4. In a device of the type described, the combination with a wash boxhaving a bed of materials therein adapted to be acted upon by a body ofwashing liquid, means for producing a pulsating flow of washingliquidthrough said bed of materials, a rotary gate for dischargingmaterials from said box, and continuously operating drive means forrotating said gate at a variable rate to control the rate of dischargeof materials, of means for introducing a control fluid directly into thewashing liquid at a point near the bottom of said bed and at pressuresvarying in proportion to the hydrostatic pressures of the washing liquidat said point, pressure amplifying means, means for establishingcommunication between said introducing means and said amplifying meansduring like portions of successive pulsations of the washing liquid,pressure fluid operated means for varying the rate at which said gate isrotated by said drive means, and means for applying the pressures fromsaid amplifying means to said pressure fluid operated means to increaseand decrease the rate of rotation of said gate and the discharge ofmaterials thereby in direct relationship with variations in thehydrostatic pressures of the washing liquid.

5. In a device of the type described, the combination of a wash boxhaving a bed of materials therein adapted to be acted upon by a body ofwashing liquid, means for producing a pulsating flow of washing liquidthrough said bed of materials, a rotary gate for discharging materialsfrom said box, and continuously operating drive means for rotating saidgate at a variable rate to control the rate of discharge of materials,of means for introducing a control fluid directly into the washingliquid at a point near the bottom of said bed and at pressures varyingin proportion to the hydrostatic pressures of the washing liquid at saidpoint, pressure responsive means, means for establishing communicationbetween said introducing means and said responsive means during likeportions of successive pulsations of the washing liquid, pressure fluidoperated means for varying the rate at which said gate is rotated bysaid drive means, a source of pressure fluid for operating said lastmentioned means, and means operated by said pressure responsive meansfor varying the pressure of the fluid from said source to cause thepressure fluid operated means to increase and decrease the rate ofrotation of said gate and the discharge of materials thereby in directrelationship with variations in the hydrostatic pressure of the washingliquid.

6. In a device of the type described, the combination with a wash boxhaving a bed of materials therein adapted to be acted upon by a body ofwashing liquid, means for producing a pulsating flow ofwashing liquidthrough said bed of materials, a rotary gate for discharging materialsfrom said box, and continuously operating drive means for rotating saidgate at a variable rate to control the rate of discharge of materials,of a pipe for continuously introducing compressed air directly into thewashing liquid at a point near the bottom of said bed, and at pressuresvarying in proportion to the hydrostatic pressure of the washing liquidat said point, a first expansible chamber in fluid communication withsaid pipe during like portions of successivepulsations of the washingliquid, a second expansible chamber operatively associated with saiddrive means for varying the rate at which said gate is rotated to varythe material discharge rate in direct relationship with the pressure insaid second chamber, a source of pressure fluid connected to said secondexpansible chamber, a bleed-off valve associated with said sourceforvarying the pressure of the fluid in said second expansible chamber,

1-2 and means. operatively connecting said first expansible chamberandsaid bleed-ofi valve to cause the latter to vary the pressure in saidsecond chamber in a direct relationship with variations in the firstchamber.

7. In a device of the type described, the combinationv with a wash boxhaving a bed of materials therein adapted,

to be acted upon by a body of washing liquid, means for producing apulsating flow of washing liquid through said bed of materials, a rotarygate for discharging materials from said box, and continuously operatingdrivemeans for rotating said gate at a variable rate to control, the.rate of discharge of materials, of a pipe for continuously introducingcompressed air directly into the washing liquid at a point near thebottom of said bed and at pressures varying in proportion to thehydrostatic pressure of the Washing liquid at said point, a pressuremeasuring device in communication with said pipe during like portions ofsuccessive pulsations 015 the. washing liquid, a pressure fluidoperated. control device. for varying the rate at which said gate isrotated by said drive means to..vary the material discharge rate indirect relationship with the pressure of the fluid applied to saidcontrol device, tubing connecting said control device to a source offluid pressure, a.bleedoff valve in said tubing for varying the pressureof the fluid applied to said control device, and means actuatedbytheoperation of said pressure measuring device for adjusting the positionof said bleed-01f valve to maintain a direct relationship between thepressure of the fluid applied to said control device and saidhydrostatic pressure of the washing liquid.

8. In a device of the type described, the combination with a wash boxhaving a bed of materials therein adapted to be acted upon by a body ofwashing liquid, means for producing a pulsating flow of washing. liquidthrough said bed of materials, a rotary gate for discharging materialsfrom said box, and continuously operating drive means forrotating said.gate at a variable rate to control .the rate of discharge of materials,of a pipe for continuously introducing compressed air directly into thewashing liquid at a point near thebottom of said bed and at pressuresvarying in proportion to the hydrostatic pressure. of the washing liquidat said point, a pressure gauge in communication with said pipe duringlike portions of successive pulsations of the washing liquid, a casinghaving a movable wall operatively connected to said drive means forvarying the rate of rotation of said gate to vary the material dischargerate in direct relationship with the fluid pressure in said casing,tubing connecting said casing to a source of fluid pressure, a pressurefluid operated bleed-cit valve in said tubing for varying the pressureof the fluid in said casing, tubing for supplying pressure fluid tooperate said valve, said last mentioned tubing having a pressureregulating vent therein, and a closure operated by said gauge to adjustthe size of said vent in accordance withthe pressure in said pipe, thesize of said vent determining the position of the bleed-off valve andthereby regulating the pressurein said casing.

9. In a device of the type described, the combination with a wash boxhaving a bed of materials therein adapted to be acted upon by a body ofwashing liquid, means for producing a pulsating flow of washing liquidthrough said bed of materials, a rotary gate for discharging materialsfrom said box, a continuously operating prime mover, and transmissionmeans including an adjustable throw step-by-step drive between saidprime mover and said gate for rotating the latter at a variable rate tocontrol the rate of discharge of materials, of means forintroducingacontrol fluid directly into and against the pressure of the washingliquid at a point at which pressure'of the washing liquid variesproportionately with changes in the hydraulic resistance of the materialbed, means for amplifying the pressures of the control fluid in saidintroducing means during like portions of successiv'ev pulsations of thewashing liquid, and pressure fluid'operating means responsive tovariations in said amplified "pressures for varying the "length or throwof said step-by-s'tep drive to increase or decrease the ratest'ep-by-step drive between said'p'rime mover and said gate for rotatingthe latter at a variable rate to control the rate of discharge ofmaterials, of means for introducing a control fluid directly into andagainstthe pres sure of the Washing liquid at 'a point 'a't which'thepressure of the washing liquid varies proportionately with changes inthehydra'ulic resistance of the material bed, means for amplifying thepressures of the control fluid in said introducing means during likeportions of successive pulsations of the washing liquid, means forfurther amplifying the previously amplified pressures of 'the controlfluid, and pressure fluid operated means responsive to variations in thefurther amplified pressures for varying the length of throw of saidstep-by-step drive to increase or decrease the rate of rotation of saidgate and the rate at which materials are discha'rgedby the gate indirect relationship with variations in the hydraulic resistance of thematerial bed.

11. In a device of the type described, the combination 'with a wash boxhaving a bed of materials'therein adapted to be acted uponby a body ofwashing liquid, means for producing *avpulsatingflow of washing liquidthrough said bed of materials, a rotary gate for discharging materialsfrom said box, a continuouslyoperating prime mover,andtra'nsmission'means'including an adjustable throw step-by-step drivebetween said prime mover and said gate for rotating the latter at avariable rate to control the rate of discharge "of materials, of meansfor introducing a control'fluid directly into the washing liquid at apoint near the bottom of said bed and at pressures varying in proportionto the hydrostatic pressures of the washing liquid at said point, afluid pressuregauge, tubing connecting said introducing means and saidgauge during like portions of successive pulsations of the washingliquid, pressure fluid operated means for varying the length of throw ofsaid step-by-step drive in direct relationship with the pressure of theoperating fluid, a source of pressure fluid for operating said lastmentioned means, means including a valve for controlling the pressure ofthe fluid from said source, and a linkage connecting said gauge and saidpressure controlling means for operating the latter to vary the pressureof the operating fluid in response to variations in the pressuremeasured by said gauge.

12. In a device of the type described, the combination with a Wash boxhaving a bed of materials therein adapted to be acted upon by a body ofwashing liquid, means for producing a pulsating flow of washing liquidthrough said bed of materials, a rotary gate for discharging materialsfrom said box, a continuously operating prime mover, and transmissionmeans including an adjustable throw step-by-step drive between saidprime mover and said gate for rotating the latter at a variable rate tocontrol the rate of discharge of materials, of a pipe for continuouslyintroducing compressed air into said washing liquid at a point near thebottom of said bed and at pressures varying in proportion to thehydrostatic pressures of the washing liquid at said point, a pressuregauge, tubing connecting the gauge to said pipe, a valve in said tubing,means for closing said valve during like major portions of successivepulsations of the washing liquid, pressure fluid operated means forvarying the length of throw of said step-by-step drive in directrelationship with the pressure of the operating fluid, tubing forsupplying pressure fluid 't'ooperate said drive adjusting means, a valvein said-supply tubing for adjusting the pressure of the operating fluid,and means operated by said pressure gauge 'for regulating the positionof said last mentioned valve to vary the pressure of the operating fluidand to cause the drive adjusting means to increase or decrease the rateof rotation of said gate in direct relationship with the variations inthepressure of the air in said pipe.

13. ha device of the type described, the combination with a Wash boxhaving a bed of materials therein adapted to be acted upon by a body ofWashing liquid, means for producing a pulsating flow of washing liquidthrough said bed or materials, a rotary gate for discharging materialsfrom said boX, a continuously operating prime mover, and transmissionmeans including an adjustable throw stepby-step drive between said primemover and said gate for rotating the latter at a variable rate tocontrol the rated discharge of materials, of a pipe for continuouslyintroducing compressed air into said washing liquid at apoint near thebottom of said bed and at pressures varying in proportion to thehydrostatic pressures of the washing liquid at said point, a pressuregauge, tubing connecting said gauge to said pipe, a valve in saidtubing, means for closingsaid valve during like major portions ofsuccessive pulsations of the washing liquid, a chamber having a movableWall the position of which is determined by the pressure of the fluidwithin the chamber, a rod connecting said movable wall to saidstep-bystep drive to adjust the length of throw of the latter inaccordance with the position of the movable wall, tubing for supplyingpressure fluid to said chamber, a valve in said supply tubing forcontrolling the pressure of the fluid in said chamber, and meansoperated by said gauge for regulating the position of said lastmentioned valve to increase or decrease the rate of rotation of saidgate in direct relationship with the variations in the pressure of theair in said pipe.

'14. In a device of the type described, the combination with a wash boxhaving a bed of materials therein adapted to be acted upon by a body ofwashing liquid, means for producing a pulsating flow of washingliquidthrough said 'bed of materials, a rotary gate for dischargingmaterials from said box, a continuously operating prime mover, andtransmission means including an adjustable throw stepby-step drivebetween said prime mover and said gate for rotating the latter at avariable rate to control the rate of discharge of materials, of a pipefor continuously introducing compressed air into said washing liquid ata point near the bottom of said bed and at pressures varying inproportion to the hydrostatic pressures of the washing liquid at saidpoint, a pressure gauge, tubing connecting said gauge to said pipe, avalve in said tubing, means for closing said valve during like majorportions of successive pulsations of the washing liquid, a chamberhaving a movable wall the position of which is determined by thepressure of the fluid within the chamber, a rod connecting said movablewall to said step-by-step drive to adjust the length of throw of thelatter in accordance with the position of the movable wall, tubing forsupplying pressure fluid to said chamber, a fluid pressure operatedvalve in said supply tubing for controlling the pressure of the fluid insaid chamber, tubing for supplying pressure fluid to said last mentionedvalve, a valve in said last mentioned tubing for controlling thepressure therein, and means operated by said gauge for regulating theposition of said last mentioned valve, the variations in the pressure ofthe air in said pipe acting through said gauge, valves, chamber and rodto increase or decrease the rate of rotation of said gate in directrelationship with variations in the hydrostatic pressure of the washingliquid.

15. A device for controlling the thickness of the high gravity stratumof the material bed in a Wash box, comprising means for discharging thehigh gravity particles from the lower portion of a material bed in awash box,

means for actuating said discharge means to cause the latter tocontinuously discharge high gravity particles,

pressure fluid operated means having a member movable in directrelationship with variations in the pressure of the operating fluid forregulating said actuating means to proportionately vary the rate ofdischarge of the high gravity particles, means for supplying fluid at avariable pressure to said regulating means, means for continuouslydischarging compressed air directly into the bottom portion of the highgravity stratum of the material bed and at pressures varying inproportion to the variable hydrostatic pressures at the point ofdischarge, and means responsive to variations in the pressures of theair in said discharge means for adjusting said fluid supply means tovary the pressure of the fluid supplied to said regulating means indirect relationship with the pressure variations in said air dischargemeans. 16. A device for controlling the thickness of the high gravitystratum of the material bed in a wash box, comprising means fordischarging the high gravity particles from the lower portion of amaterial bed in a wash box, means for actuating said discharge means tocause the lat- "ter to continuously discharge high gravity particles,means for regulating said actuating means 'to control the rate ofdischarge of the high gravity particles, a pipe for con tinuouslydischarging compressed air directly into the bottom of the high gravitystratum of the material bed and at pressures varying in proportion tothe variable hydrostatic pressures at said point, means for amplifyingthe pressures of the air in said pipe, means for adjusting saidregulating means to increase or decrease the rate of discharge of thehigh gravity particles to its maximum and minimum values, respectively,and to a plurality of intermediate values, and means responsive tovariations in said amplified pressures for operating said adjustingmeans to vary the rate of discharge in direct relationship withvariations in said hydrostatic pressures.

17. A device for controlling the thickness of the high gravity stratumof the material bed in a wash box, comprising means for discharging thehigh gravity particles from the lower portion of the material bed in awash box, means for actuating said discharge means to cause the latterto continuously discharge high gravity particles, means for regulatingsaid actuating means to control the rate of discharge of the highgravity particles, a pipe for continuously discharging compressed airdirectly into the bottom portion of the high gravity stratum of thematerial bed and at pressures varying in proportion to the variablehydrostatic pressures at said point, means for amplifying the pressuresof the air in said pipe, fluid pressure operated means for adjustingsaid regulating means to increase or decrease the rate of discharge ofthe high gravity particles to its maximum and minimum values,respectively, and to a plurality of intermediate values, and valve meansresponsive to variations in said amplified pressures for varying thefluid pressure applied to said adjusting means to cause the rate ofdischarge to be varied in direct relationship with variations in saidhydrostatic pressures.

18. A device for controlling the thickness of the high gravity stratumof a material bed in a wash box, comprising means for discharging thehigh gravity particles from the lower portion of a material bed in awash box, means for actuating said discharge means to cause the latterto continuously discharge high gravity particles, pressure fluidoperated means for regulating said actuating means to control the rateof discharge of the high gravity particles, apipe for continuouslydischarging compressed air directly into the bottom portion of the highgravity stratum of the material bed and atpressures varying inproportion to the variable hydrostatic pressures at said point, tubingconnecting said pipe to a source of compressed air, means mountedinvsaid tubing for maintaining the rate of flow of air into said pipe ata constant value, tubing connecting said pressure fluid operated meansto said source of compressed air, and means associated with said lastmentioned tubing and responsive to the pressures of the air in said pipefor adjusting the pressure of the air delivered to said pressure fluidoperated means to increase or decrease the rate of discharge by amountsthat are directly proportional to variations in said hydrostaticpressures.

References Cited in the file of this patent UNITED STATES PATENTS BrentzOct. 27, 1942 Lotz Aug. 12, 1952 7 Inc., Albany, New York, 1947, pages54-76. (Copy in Division 30.)

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